(1) Field of the Invention
The present invention relates generally to semiconductor wafer handling and storage, and more particularly to a new wafer container that facilitates loading and unloading large size wafers.
(2) Description of the Prior Art
The transport and storage of semiconductor wafers has presented more problems as the diameter of the wafers has increased in size, and the circuitry has become more microminiaturized. The wafer size has increased from one and a quarter inches in diameter to eight inches in diameter. The metallurgy on the wafer and the thickness of the protective insulation layers has at the same time decreased by orders of magnitude. These developments have produced wafers that have a much greater mass, and a circuitry structure that is much more sensitive to stress, vibration and abrasion.
U.S. Pat. No. 5,366,079 to Lin represents a recent improvement in wafer carriers that is designed for storing and transporting semiconductor wafers having large diameters. However, some difficulty has been experienced in the loading and unloading of the wafer carrier. In loading, the wafer must be grasped with a vacuum pen, or similar implement, and either lowered into the container, raise through a top opening. This presents the possibility of dropping the wafer and damaging both the wafer that falls, as well as the wafer absorbing the shock. In addition, in placing the wafer on the stack of wafers in the container an edge of the wafer can scrape the surface of the top wafer in the stack to damage the wafer. In addition, lowering the wafers through a top opening is a time consuming and tedious task.